diff options
| -rw-r--r-- | fs/pipe.c | 51 |
1 files changed, 33 insertions, 18 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index c16950e36ded..ce77ac0d8901 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -387,7 +387,7 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) { struct file *filp = iocb->ki_filp; struct pipe_inode_info *pipe = filp->private_data; - unsigned int head, tail, max_usage, mask; + unsigned int head, max_usage, mask; ssize_t ret = 0; int do_wakeup = 0; size_t total_len = iov_iter_count(from); @@ -405,14 +405,13 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) goto out; } - tail = pipe->tail; head = pipe->head; max_usage = pipe->max_usage; mask = pipe->ring_size - 1; /* We try to merge small writes */ chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */ - if (!pipe_empty(head, tail) && chars != 0) { + if (!pipe_empty(head, pipe->tail) && chars != 0) { struct pipe_buffer *buf = &pipe->bufs[(head - 1) & mask]; int offset = buf->offset + buf->len; @@ -441,8 +440,8 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) break; } - tail = pipe->tail; - if (!pipe_full(head, tail, max_usage)) { + head = pipe->head; + if (!pipe_full(head, pipe->tail, max_usage)) { struct pipe_buffer *buf = &pipe->bufs[head & mask]; struct page *page = pipe->tmp_page; int copied; @@ -455,40 +454,56 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) } pipe->tmp_page = page; } + + /* Allocate a slot in the ring in advance and attach an + * empty buffer. If we fault or otherwise fail to use + * it, either the reader will consume it or it'll still + * be there for the next write. + */ + spin_lock_irq(&pipe->wait.lock); + + head = pipe->head; + pipe->head = head + 1; + /* Always wake up, even if the copy fails. Otherwise * we lock up (O_NONBLOCK-)readers that sleep due to * syscall merging. * FIXME! Is this really true? */ - do_wakeup = 1; - copied = copy_page_from_iter(page, 0, PAGE_SIZE, from); - if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) { - if (!ret) - ret = -EFAULT; - break; - } - ret += copied; + wake_up_interruptible_sync_poll_locked( + &pipe->wait, EPOLLIN | EPOLLRDNORM); + + spin_unlock_irq(&pipe->wait.lock); + kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); /* Insert it into the buffer array */ + buf = &pipe->bufs[head & mask]; buf->page = page; buf->ops = &anon_pipe_buf_ops; buf->offset = 0; - buf->len = copied; + buf->len = 0; buf->flags = 0; if (is_packetized(filp)) { buf->ops = &packet_pipe_buf_ops; buf->flags = PIPE_BUF_FLAG_PACKET; } - - head++; - pipe->head = head; pipe->tmp_page = NULL; + copied = copy_page_from_iter(page, 0, PAGE_SIZE, from); + if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) { + if (!ret) + ret = -EFAULT; + break; + } + ret += copied; + buf->offset = 0; + buf->len = copied; + if (!iov_iter_count(from)) break; } - if (!pipe_full(head, tail, max_usage)) + if (!pipe_full(head, pipe->tail, max_usage)) continue; /* Wait for buffer space to become available. */ |